Effect of clouds on photolysis and oxidants in the troposphere
Identifieur interne : 000063 ( Istex/Corpus ); précédent : 000062; suivant : 000064Effect of clouds on photolysis and oxidants in the troposphere
Auteurs : Xuexi Tie ; Sasha Madronich ; Stacy Walters ; Renyi Zhang ; Phil Rasch ; William CollinsSource :
- Journal of Geophysical Research: Atmospheres [ 0148-0227 ] ; 2003-10-27.
Abstract
Cloud layers in the troposphere influence photolysis rates (J values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH4 lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of J[O3], J[CH2O], and J[NO2] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O3 concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.
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DOI: 10.1029/2003JD003659
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title xml:lang="en">Effect of clouds on photolysis and oxidants in the troposphere</title><author><name sortKey="Tie, Xuexi" sort="Tie, Xuexi" uniqKey="Tie X" first="Xuexi" last="Tie">Xuexi Tie</name><affiliation><mods:affiliation>E-mail: xxtie@ucar.edu</mods:affiliation></affiliation><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Madronich, Sasha" sort="Madronich, Sasha" uniqKey="Madronich S" first="Sasha" last="Madronich">Sasha Madronich</name><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Walters, Stacy" sort="Walters, Stacy" uniqKey="Walters S" first="Stacy" last="Walters">Stacy Walters</name><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Zhang, Renyi" sort="Zhang, Renyi" uniqKey="Zhang R" first="Renyi" last="Zhang">Renyi Zhang</name><affiliation><mods:affiliation>Department of Atmospheric Sciences, Texas A&M University, Texas, College Station, USA</mods:affiliation></affiliation></author><author><name sortKey="Rasch, Phil" sort="Rasch, Phil" uniqKey="Rasch P" first="Phil" last="Rasch">Phil Rasch</name><affiliation><mods:affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Collins, William" sort="Collins, William" uniqKey="Collins W" first="William" last="Collins">William Collins</name><affiliation><mods:affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:0DEFD890BBA76BF14E03596922F1962D7AF14820</idno><date when="2003" year="2003">2003</date><idno type="doi">10.1029/2003JD003659</idno><idno type="url">https://api.istex.fr/document/0DEFD890BBA76BF14E03596922F1962D7AF14820/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">000063</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a" type="main" xml:lang="en">Effect of clouds on photolysis and oxidants in the troposphere</title><author><name sortKey="Tie, Xuexi" sort="Tie, Xuexi" uniqKey="Tie X" first="Xuexi" last="Tie">Xuexi Tie</name><affiliation><mods:affiliation>E-mail: xxtie@ucar.edu</mods:affiliation></affiliation><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Madronich, Sasha" sort="Madronich, Sasha" uniqKey="Madronich S" first="Sasha" last="Madronich">Sasha Madronich</name><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Walters, Stacy" sort="Walters, Stacy" uniqKey="Walters S" first="Stacy" last="Walters">Stacy Walters</name><affiliation><mods:affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Zhang, Renyi" sort="Zhang, Renyi" uniqKey="Zhang R" first="Renyi" last="Zhang">Renyi Zhang</name><affiliation><mods:affiliation>Department of Atmospheric Sciences, Texas A&M University, Texas, College Station, USA</mods:affiliation></affiliation></author><author><name sortKey="Rasch, Phil" sort="Rasch, Phil" uniqKey="Rasch P" first="Phil" last="Rasch">Phil Rasch</name><affiliation><mods:affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Collins, William" sort="Collins, William" uniqKey="Collins W" first="William" last="Collins">William Collins</name><affiliation><mods:affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Journal of Geophysical Research: Atmospheres</title><title level="j" type="abbrev">J. Geophys. Res.</title><idno type="ISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="2003-10-27">2003-10-27</date><biblScope unit="volume">108</biblScope><biblScope unit="issue">D20</biblScope><biblScope unit="page" from="n/a">n/a</biblScope><biblScope unit="page" to="n/a">n/a</biblScope></imprint><idno type="ISSN">0148-0227</idno></series><idno type="istex">0DEFD890BBA76BF14E03596922F1962D7AF14820</idno><idno type="DOI">10.1029/2003JD003659</idno><idno type="ArticleID">2003JD003659</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0148-0227</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">Cloud layers in the troposphere influence photolysis rates (J values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH4 lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of J[O3], J[CH2O], and J[NO2] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O3 concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.</div></front></TEI><istex><corpusName>wiley</corpusName><author><json:item><name>Xuexi Tie</name><affiliations><json:string>E-mail: xxtie@ucar.edu</json:string><json:string>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>Sasha Madronich</name><affiliations><json:string>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>Stacy Walters</name><affiliations><json:string>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>Renyi Zhang</name><affiliations><json:string>Department of Atmospheric Sciences, Texas A&M University, Texas, College Station, USA</json:string></affiliations></json:item><json:item><name>Phil Rasch</name><affiliations><json:string>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>William Collins</name><affiliations><json:string>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>clouds</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>photolysis</value></json:item></subject><language><json:string>eng</json:string></language><abstract>Cloud layers in the troposphere influence photolysis rates (J values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH4 lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of J[O3], J[CH2O], and J[NO2] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O3 concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.</abstract><qualityIndicators><score>8</score><pdfVersion>1.3</pdfVersion><pdfPageSize>592 x 807 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>2</keywordCount><abstractCharCount>2553</abstractCharCount><pdfWordCount>10572</pdfWordCount><pdfCharCount>60578</pdfCharCount><pdfPageCount>25</pdfPageCount><abstractWordCount>394</abstractWordCount></qualityIndicators><title>Effect of clouds on photolysis and oxidants in the troposphere</title><genre><json:string>article</json:string></genre><host><volume>108</volume><pages><total>22</total><last>n/a</last><first>n/a</first></pages><issn><json:string>0148-0227</json:string></issn><issue>D20</issue><subject><json:item><value>Aerosol and Clouds</value></json:item><json:item><value>ATMOSPHERIC COMPOSITION AND STRUCTURE</value></json:item><json:item><value>Aerosols and particles</value></json:item><json:item><value>Chemical kinetic and photochemical properties</value></json:item><json:item><value>Cloud physics and chemistry</value></json:item><json:item><value>Constituent sources and sinks</value></json:item><json:item><value>Pollution: urban and regional</value></json:item><json:item><value>OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL</value></json:item><json:item><value>Aerosols</value></json:item><json:item><value>PALEOCEANOGRAPHY</value></json:item><json:item><value>Aerosols</value></json:item><json:item><value>Aerosols and Clouds</value></json:item></subject><genre></genre><language><json:string>unknown</json:string></language><eissn><json:string>2156-2202</json:string></eissn><title>Journal of Geophysical Research: Atmospheres</title><doi><json:string>10.1002/(ISSN)2156-2202d</json:string></doi></host><publicationDate>2003</publicationDate><copyrightDate>2003</copyrightDate><doi><json:string>10.1029/2003JD003659</json:string></doi><id>0DEFD890BBA76BF14E03596922F1962D7AF14820</id><fulltext><json:item><original>true</original><mimetype>application/pdf</mimetype><extension>pdf</extension><uri>https://api.istex.fr/document/0DEFD890BBA76BF14E03596922F1962D7AF14820/fulltext/pdf</uri></json:item><json:item><original>false</original><mimetype>application/zip</mimetype><extension>zip</extension><uri>https://api.istex.fr/document/0DEFD890BBA76BF14E03596922F1962D7AF14820/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/0DEFD890BBA76BF14E03596922F1962D7AF14820/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a" type="main" xml:lang="en">Effect of clouds on photolysis and oxidants in the troposphere</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>Blackwell Publishing Ltd</publisher><availability><p>WILEY</p></availability><date>2003</date></publicationStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a" type="main" xml:lang="en">Effect of clouds on photolysis and oxidants in the troposphere</title><author><persName><forename type="first">Xuexi</forename><surname>Tie</surname></persName><email>xxtie@ucar.edu</email><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">Sasha</forename><surname>Madronich</surname></persName><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">Stacy</forename><surname>Walters</surname></persName><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">Renyi</forename><surname>Zhang</surname></persName><affiliation>Department of Atmospheric Sciences, Texas A&M University, Texas, College Station, USA</affiliation></author><author><persName><forename type="first">Phil</forename><surname>Rasch</surname></persName><affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">William</forename><surname>Collins</surname></persName><affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author></analytic><monogr><title level="j">Journal of Geophysical Research: Atmospheres</title><title level="j" type="abbrev">J. Geophys. Res.</title><idno type="pISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><idno type="DOI">10.1002/(ISSN)2156-2202d</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="2003-10-27"></date><biblScope unit="volume">108</biblScope><biblScope unit="issue">D20</biblScope><biblScope unit="page" from="n/a">n/a</biblScope><biblScope unit="page" to="n/a">n/a</biblScope></imprint></monogr><idno type="istex">0DEFD890BBA76BF14E03596922F1962D7AF14820</idno><idno type="DOI">10.1029/2003JD003659</idno><idno type="ArticleID">2003JD003659</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>2003</date></creation><langUsage><language ident="en">en</language></langUsage><abstract><p>Cloud layers in the troposphere influence photolysis rates (J values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH4 lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of J[O3], J[CH2O], and J[NO2] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O3 concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.</p></abstract><textClass><keywords scheme="keyword"><list><head>Keywords</head><item><term>clouds</term></item><item><term>photolysis</term></item></list></keywords></textClass><textClass><keywords scheme="Journal Subject"><list><head>Index Terms</head><item><term>Aerosol and Clouds</term></item><item><term>ATMOSPHERIC COMPOSITION AND STRUCTURE</term></item><item><term>Aerosols and particles</term></item><item><term>Chemical kinetic and photochemical properties</term></item><item><term>Cloud physics and chemistry</term></item><item><term>Constituent sources and sinks</term></item><item><term>Pollution: urban and regional</term></item><item><term>OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL</term></item><item><term>Aerosols</term></item><item><term>PALEOCEANOGRAPHY</term></item><item><term>Aerosols</term></item></list></keywords></textClass><textClass><keywords scheme="Journal Subject"><list><head>article category</head><item><term>Aerosols and Clouds</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="2003-04-03">Received</change><change when="2003-07-14">Registration</change><change when="2003-10-27">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><original>false</original><mimetype>text/plain</mimetype><extension>txt</extension><uri>https://api.istex.fr/document/0DEFD890BBA76BF14E03596922F1962D7AF14820/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Wiley, elements deleted: body"><istex:xmlDeclaration>version="1.0" encoding="UTF-8" standalone="yes"</istex:xmlDeclaration><istex:document><component type="serialArticle" version="2.0" xml:lang="en" xml:id="jgrd10709"><header><publicationMeta level="product"><doi>10.1002/(ISSN)2156-2202d</doi><issn type="print">0148-0227</issn><issn type="electronic">2156-2202</issn><idGroup><id type="product" value="JGRD"></id><id type="coden" value="JGREA2"></id></idGroup><titleGroup><title type="main" xml:lang="en" sort="JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES">Journal of Geophysical Research: Atmospheres</title><title type="short">J. 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Res.</title></titleGroup></publicationMeta><publicationMeta level="part" position="200"><doi>10.1002/jgrd.v108.D20</doi><idGroup><id type="focusSection" value="4"></id></idGroup><titleGroup><title type="focusSection" xml:lang="en">Journal of Geophysical Research: Atmospheres</title></titleGroup><numberingGroup><numbering type="journalVolume" number="108">108</numbering><numbering type="journalIssue">D20</numbering></numberingGroup><coverDate startDate="2003-10-27">27 October 2003</coverDate></publicationMeta><publicationMeta level="unit" position="30" type="article" status="forIssue"><doi>10.1029/2003JD003659</doi><idGroup><id type="editorialOffice" value="2003JD003659"></id><id type="society" value="4642"></id><id type="unit" value="JGRD10709"></id></idGroup><countGroup><count type="pageTotal" number="22"></count></countGroup><titleGroup><title type="articleCategory">Aerosols and Clouds</title><title type="tocHeading1">Aerosols and Clouds</title></titleGroup><copyright ownership="thirdParty">Copyright 2003 by the American Geophysical Union.</copyright><eventGroup><event type="manuscriptReceived" date="2003-04-03"></event><event type="manuscriptRevised" date="2003-07-02"></event><event type="manuscriptAccepted" date="2003-07-14"></event><event type="firstOnline" date="2003-10-25"></event><event type="publishedOnlineFinalForm" date="2003-10-25"></event><event type="xmlConverted" agent="SPi Global Converter:AGUv3.42_TO_WileyML3Gv1.0.3 version:1.2; AGU2WileyML3G Final Clean Up v1.0; WileyML 3G Packaging Tool v1.0" date="2012-12-20"></event><event type="xmlConverted" agent="Converter:WILEY_ML3G_TO_WILEY_ML3GV2 version:3.8.8" date="2014-01-30"></event><event type="xmlConverted" agent="Converter:WML3G_To_WML3G version:4.1.7 mode:FullText,remove_FC" date="2014-10-30"></event></eventGroup><numberingGroup><numbering type="pageFirst">n/a</numbering><numbering type="pageLast">n/a</numbering></numberingGroup><subjectInfo><subject href="http://psi.agu.org/subset/AAC">Aerosol and Clouds</subject><subject href="http://psi.agu.org/taxonomy5/0300">ATMOSPHERIC COMPOSITION AND STRUCTURE</subject><subjectInfo><subject href="http://psi.agu.org/taxonomy5/0305">Aerosols and particles</subject><subject href="http://psi.agu.org/taxonomy5/0317">Chemical kinetic and photochemical properties</subject><subject href="http://psi.agu.org/taxonomy5/0320">Cloud physics and chemistry</subject><subject href="http://psi.agu.org/taxonomy5/0322">Constituent sources and sinks</subject><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/0345">Pollution: urban and regional</subject></subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/4800">OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL</subject><subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/4801">Aerosols</subject></subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/4900">PALEOCEANOGRAPHY</subject><subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/4906">Aerosols</subject></subjectInfo></subjectInfo><selfCitationGroup><citation xml:id="jgrd10709-cit-0000" type="self"><author><familyName>Tie</familyName>, <givenNames>X.</givenNames></author>, <author><givenNames>S.</givenNames> <familyName>Madronich</familyName></author>, <author><givenNames>S.</givenNames> <familyName>Walters</familyName></author>, <author><givenNames>R.</givenNames> <familyName>Zhang</familyName></author>, <author><givenNames>P.</givenNames> <familyName>Racsh</familyName></author>, and <author><givenNames>W.</givenNames> <familyName>Collins</familyName></author> (<pubYear year="2003">2003</pubYear>), <articleTitle>Effect of clouds on photolysis and oxidants in the troposphere</articleTitle>, <journalTitle>J. Geophys. Res.</journalTitle>, <vol>108</vol>, 4642, doi:<accessionId ref="info:doi/10.1029/2003JD003659">10.1029/2003JD003659</accessionId>, <issue>D20</issue>.</citation></selfCitationGroup><linkGroup><link type="toTypesetVersion" href="file:JGRD.JGRD10709.pdf"></link></linkGroup></publicationMeta><contentMeta><countGroup><count type="figureTotal" number="20"></count><count type="tableTotal" number="4"></count></countGroup><titleGroup><title type="main">Effect of clouds on photolysis and oxidants in the troposphere</title><title type="short">EFFECT OF CLOUDS ON OXIDANTS</title><title type="shortAuthors">Tie <i>et al</i>.</title></titleGroup><creators><creator creatorRole="author" xml:id="jgrd10709-cr-0001" affiliationRef="#jgrd10709-aff-0001"><personName><givenNames>Xuexi</givenNames> <familyName>Tie</familyName></personName><contactDetails><email normalForm="xxtie@ucar.edu">xxtie@ucar.edu</email></contactDetails></creator><creator creatorRole="author" xml:id="jgrd10709-cr-0002" affiliationRef="#jgrd10709-aff-0001"><personName><givenNames>Sasha</givenNames> <familyName>Madronich</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd10709-cr-0003" affiliationRef="#jgrd10709-aff-0001"><personName><givenNames>Stacy</givenNames> <familyName>Walters</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd10709-cr-0004" affiliationRef="#jgrd10709-aff-0002"><personName><givenNames>Renyi</givenNames> <familyName>Zhang</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd10709-cr-0005" affiliationRef="#jgrd10709-aff-0003"><personName><givenNames>Phil</givenNames> <familyName>Rasch</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd10709-cr-0006" affiliationRef="#jgrd10709-aff-0003"><personName><givenNames>William</givenNames> <familyName>Collins</familyName></personName></creator></creators><affiliationGroup><affiliation countryCode="US" type="organization" xml:id="jgrd10709-aff-0001"><orgDiv>Atmospheric Chemistry Division</orgDiv><orgName>National Center for Atmospheric Research</orgName><address><city>Boulder</city><countryPart>Colorado</countryPart><country>USA</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd10709-aff-0002"><orgDiv>Department of Atmospheric Sciences</orgDiv><orgName>Texas A&M University</orgName><address><city>College Station</city><countryPart>Texas</countryPart><country>USA</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd10709-aff-0003"><orgDiv>Climate and Global Dynamics Division</orgDiv><orgName>National Center for Atmospheric Research</orgName><address><city>Boulder</city><countryPart>Colorado</countryPart><country>USA</country></address></affiliation></affiliationGroup><keywordGroup type="author"><keyword xml:id="jgrd10709-kwd-0001">clouds</keyword><keyword xml:id="jgrd10709-kwd-0002">photolysis</keyword></keywordGroup><supportingInformation></supportingInformation><abstractGroup><abstract type="main"><p xml:id="jgrd10709-para-0001" label="1">Cloud layers in the troposphere influence photolysis rates (<i>J</i> values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH<sub>4</sub> lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of <i>J</i>[O<sub>3</sub>], <i>J</i>[CH<sub>2</sub>O], and <i>J</i>[NO<sub>2</sub>] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O<sub>3</sub> concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.</p></abstract></abstractGroup></contentMeta></header></component></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>Effect of clouds on photolysis and oxidants in the troposphere</title></titleInfo><titleInfo type="abbreviated"><title>EFFECT OF CLOUDS ON OXIDANTS</title></titleInfo><titleInfo type="alternative" contentType="CDATA" lang="en"><title>Effect of clouds on photolysis and oxidants in the troposphere</title></titleInfo><name type="personal"><namePart type="given">Xuexi</namePart><namePart type="family">Tie</namePart><affiliation>E-mail: xxtie@ucar.edu</affiliation><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Sasha</namePart><namePart type="family">Madronich</namePart><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Stacy</namePart><namePart type="family">Walters</namePart><affiliation>Atmospheric Chemistry Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Renyi</namePart><namePart type="family">Zhang</namePart><affiliation>Department of Atmospheric Sciences, Texas A&M University, Texas, College Station, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Phil</namePart><namePart type="family">Rasch</namePart><affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">William</namePart><namePart type="family">Collins</namePart><affiliation>Climate and Global Dynamics Division, National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="article">article</genre><originInfo><publisher>Blackwell Publishing Ltd</publisher><dateIssued encoding="w3cdtf">2003-10-27</dateIssued><dateCaptured encoding="w3cdtf">2003-04-03</dateCaptured><dateValid encoding="w3cdtf">2003-07-14</dateValid><edition>Tie, X., S. Madronich, S. Walters, R. Zhang, P. Racsh, and W. Collins (2003), Effect of clouds on photolysis and oxidants in the troposphere, J. Geophys. Res., 108, 4642, doi:10.1029/2003JD003659, D20.</edition><copyrightDate encoding="w3cdtf">2003</copyrightDate></originInfo><language><languageTerm type="code" authority="rfc3066">en</languageTerm><languageTerm type="code" authority="iso639-2b">eng</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType><extent unit="figures">20</extent><extent unit="tables">4</extent></physicalDescription><abstract>Cloud layers in the troposphere influence photolysis rates (J values) and hence concentrations of chemical species. In order to study the impact of clouds on photolysis rates and oxidants, we have developed a simplified version of the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet‐Visible (TUV) model and have coupled the simplified TUV (otherwise known as the fast TUV (FTUV)) into the NCAR/Atmospheric Chemistry Division global transport chemical model (Model for Ozone and Related Chemical Tracers (MOZART‐2)). The FTUV model has the same physical processes as the TUV model, except that the wavelength bins between 121 and 750 nm are reduced from 140 to 17. As a result, FTUV is about 8 times faster than the original TUV. Differences in the calculated photolysis rates between TUV and FTUV are generally less than 5% in the troposphere. Subgrid vertical distributions of clouds are also considered in the calculation of photolysis rates in MOZART‐2. The method used in this study is a mixed maximum and random overlap scheme. The subgrid method increases the computation time for photolysis rates by a factor of 3 compared to a simple method in which clouds are uniformly distributed over the MOZART‐2 grids. Our calculation shows that the uniform cloud distribution method tends to significantly overestimate back scattering on the top of clouds and overestimates the impact on photochemistry in the troposphere. The results suggest that clouds have important impacts on tropospheric chemistry. Global mean OH concentration increases by about 20% due to the impact of clouds. As a result, the calculated CH4 lifetime changes to 11 years for clear sky and 9 years for cloudy sky. The latter value is closer to the methane lifetime estimated from previous studies. Calculated CO surface concentrations are compared with observed values, showing an improvement when the impact of clouds on the photolysis rates is taken into account. Clouds also have important impacts on tropospheric ozone budget. Our calculation suggest that because of clouds, the globally averaged photolysis rates of J[O3], J[CH2O], and J[NO2] are enhanced in the troposphere by about 12, 13, and 13%, respectively, leading to an 8% increase in the tropospheric O3 concentrations. Our study suggests that clouds strongly influence photolysis rates and hence play an important role in controlling the concentrations of the tropospheric oxidants. Such effects should be carefully considered and included in regional and global chemical transport models.</abstract><subject><genre>Keywords</genre><topic>clouds</topic><topic>photolysis</topic></subject><relatedItem type="host"><titleInfo><title>Journal of Geophysical Research: Atmospheres</title></titleInfo><titleInfo type="abbreviated"><title>J. Geophys. Res.</title></titleInfo><subject><genre>Index Terms</genre><topic authorityURI="http://psi.agu.org/subset/AAC">Aerosol and Clouds</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0300">ATMOSPHERIC COMPOSITION AND STRUCTURE</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0305">Aerosols and particles</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0317">Chemical kinetic and photochemical properties</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0320">Cloud physics and chemistry</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0322">Constituent sources and sinks</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0345">Pollution: urban and regional</topic><topic authorityURI="http://psi.agu.org/taxonomy5/4800">OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL</topic><topic authorityURI="http://psi.agu.org/taxonomy5/4801">Aerosols</topic><topic authorityURI="http://psi.agu.org/taxonomy5/4900">PALEOCEANOGRAPHY</topic><topic authorityURI="http://psi.agu.org/taxonomy5/4906">Aerosols</topic></subject><subject><genre>article category</genre><topic>Aerosols and Clouds</topic></subject><identifier type="ISSN">0148-0227</identifier><identifier type="eISSN">2156-2202</identifier><identifier type="DOI">10.1002/(ISSN)2156-2202d</identifier><identifier type="CODEN">JGREA2</identifier><identifier type="PublisherID">JGRD</identifier><part><date>2003</date><detail type="volume"><caption>vol.</caption><number>108</number></detail><detail type="issue"><caption>no.</caption><number>D20</number></detail><extent unit="pages"><start>n/a</start><end>n/a</end><total>22</total></extent></part></relatedItem><identifier type="istex">0DEFD890BBA76BF14E03596922F1962D7AF14820</identifier><identifier type="DOI">10.1029/2003JD003659</identifier><identifier type="ArticleID">2003JD003659</identifier><accessCondition type="use and reproduction" contentType="copyright">Copyright 2003 by the American Geophysical Union.</accessCondition><recordInfo><recordContentSource>WILEY</recordContentSource></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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